This invention concerns a novel system for treating sickle cell disease and, more particularly, a substantially continuous system for carbamylating red blood cells to therapeutically treat sickle cell disease.
Sickle cell disease concerns a human blood disorder in which the red blood cells contain hemoglobin S, which is an abnormal hemoglobin. On occasion, the hemoglobin S cells change from the normal disc shape to a crescent shape, and these cells are designated sickle cells. There are presently certain known methods of treating sickle cell disease with an extracorporeal carbamylation method.
One prior art method of treating sickle cell disease by carbamylating red blood cells utilizes a batch process by which a predetermined amount of whole blood is removed from the patient, the whole blood is treated and thereafter the treated blood is reinfused. This prior art method requires the steps of erythropheresing the patient with blood bags, separating the red blood cells with centrifugation and carbamylating the cells by short incubation with an anti-sickle agent, such as a cyanate solution, washing the otherwise toxic carbamylating agent with manual centrifugation and decanting, reconstituting the carbamylated cells with plasma, reinfusing the reconstitate, and repeating this batch process as many times as possible during one day.
In the batch processing described in U.S. Pat. No. 3,833,724, a unit of the patient's blood is removed into a bag containing acid-citrate-dextrose (ACD). The blood is then centrifuged and the plasma is returned to the patient. The recovered red cells are incubated with an aqueous solution of sodium cyanate (0.001 M to 0.01 M) at about 37.degree. C. for about one to two hours. The cells are then washed to remove any unreacted cyanate and the resulting carbamylated cells are then reintroduced into the patient.
The aforesaid type of batch treatment process is labor intensive and time consuming. Typically, no more than three patients can be treated in one day at one blood treatment center. Because of the batch nature of the process, patients are treated relatively inefficiently, typically having less than 20 percent of their cells carbamylated. The process is merely a treatment that prevents sickling of those cells which have been carbamylated. As these cells age and deteriorate, they are replaced by new sickle-able cells which must then be likewise treated.
We have discovered that a continuous sickle cell treatment process would increase the efficiency of treating sickle cell disease. While in the batch processing extracorporeal blood volumes must be kept low, this problem is overcome using continuous processing.
It is, therefore, an object of the present invention to provide a novel system for treating sickle cell disease utilizing continuous flow red blood cell carbamylation.
Another object of the present invention is to provide a red blood cell carbamylation process that is simple in operation and does not require the removal of substantial extracorporeal blood volumes.
A further object of the present invention is to provide a continuously flowing centrifugal system to partition red blood cells to be treated from the whole blood of a sickle cell patient, and to treat the red blood cells with anti-sickle agents, to wash these agents from the red blood cells and to finally return the red blood cells to the patient.
Other objects and advantages of the present invention will become apparent as the description proceeds.